baking normal maps for games. Smooth shading issues
If you get the bakes that looks good they should be fine. If it's a glossy surface then you can get stair casing in the normals where they are nearly flat since 8-bit reproduces only a limited number of angles. The simplest way is to add hard edges the windows edge to make it perfectly flat.

Triangulate meshes before baking them. Software does not always agree how to split the faces so it's good to make sure you decide.

You should avoid thin triangles. Thin triangles can act as a hard edge since they usually don't get enough pixels to bend where normals changes. Perfectly flat surfaces with no normal changes can handle thin triangles though.

Separate all hard edged faces on separate UV-islands and give them enough margin.
If they are to close they might fight over the pixels. Remember that mip-maps will be in lower resolution.

Align bevels and other details with pixels where possible. Prioritise sharper bevels.

Give detailed areas of your mesh a bit more UV space so the smaller triangles will get what they need.

You can get distortions and other artefacts where the normals bends but I think it's better if you encounter them, figuring out way they appear and how to mitigate them.